This invention relates to an electric motor-driven timer with a contact actuator for moving movable blades with movable contacts.
In an electric motor-driven timer in the well known prior art, timing contacts are closed or opened by a contact actuator when a driven-gear, set in a desired position through a time-setting means, is rotated to a predetermined position by receiving a rotating force from a synchronous motor through a clutch means. The actuator is pivotably fixed at one end and engages with movable blades at another end, and is provided with a cam follower at an intermediate position between the two ends. The cam follower of the actuator touches on a cam surface of the driven-gear and falls in a groove or a cut-out portion when a preset time has passed, so that the actuator drives the movable blades.
Such timer, however, has the disadvantage of unstable characteristics due to chattering, since the arm of the contact actuator is pivotably fixed at one end and the arm is long.
Another disadvantage is that such timer is not operable in two operation modes, i.e. a self-return type and an electromagnet-return type, that is, whether the contact actuator is operable under energization of an electromagnet or operable under deenergization of the electromagnet. In other words, it was very expensive to manufacture two types of timers which are substantially different in construction.
Therefore, it is an object of this invention to provide an electric motor-driven timer with stable characteristics.
It is another object of this invention to provide an electric motor-driven timer which is operable in a choice of two operation modes.
It is another object of this invention to provide a compact electric motor-driven timer.